Copper inlays

[Adillo303]

I tried my first pen with a copper inlay.

I made a sandwich of black walnut / Copper / Hard white Maple. I glued with 5 minute epoxy, clamped it and let it sit half an hour. It seemed to go well, or so I thought.

I took my blank and cut a diagonal, laid the sandwich in the cut, used 5 minutes epoxy, clamped and let sit half hour. It looked good, felt solid, so I thought that I would drill it and let it sit overnight.

While drilling, the sandwich came apart between the copper and the black walnut. That particular joint had over an hour to set.

Any suggestions as to what I did wrong and what I should do to make this work would be appreciated.

Thank you
Andy

 

[rossvh]

Not sure, but I've done this multiple times before with both CA and 5 minute epoxy and the only time it separated while drilling was when I "rushed" the curing time. Typically I found that the drilling puts so much pressure on the joints that now I wait overnight before drilling just to make sure the metal has fully cured.
RossVH

 

[Adillo303]

That is what I was sorry of thinking.

Thank you.

 

[plano_harry]

Andy, many possible explanations. Did you rough up the copper to get a better bond? How thick was the copper? Metal heats very quickly when drilling and can destroy a glue bond. Diagonals are particularly difficult. Your best bet is to do several searches on segmenting using different terms and read all the comments.

In general, you need to drill very gently, low pressure, short periods followed by cooling periods for the metal and the drill. Sharp bits. Try starting with a small bit and work your way up gradually. Another approach is to glue on popsicle stick splints on all four sides to strengthen the joint while you drill. For longitudinal segments, try wrapping the blank with thread or twine and CA all over it. There are lots of tricks, but nothing that works in every case.

Harry

 

[BSea]

Or, it may have been the heat from drilling caused the glue to fail. Both CA and epoxy will fail if they get too hot. try wrapping the lank with rubber bands or tape when you drill. And go slow.

edit: Harry beat me to it.

 

[Adillo303]

The copper is something like .021". I do drill slowly (700) rpm. I did not think to rest and let this cool. makes sense though, copper conducts heat faster than about anything.

when I joined the Air Force a bunch of years ago, my DI always used to say "Hurry and F___ up." it has haunted me all my life.


I thank all of you for the help. Fortunately, I have more of the blank material available.

While I am asking questions. you you all have similar results with epoxy and CA, or do you find one better than the other?

 

[plano_harry]

Back when I was crying this tune, Hank Lee told me that he may spend an entire day drilling a segmented blank. Well I can't go that slow, I would explode before the blank did, but you have to really take it easy. I wasn't so much referring to the rpm, as to just a light touch and then back off to cool. I often put DNA on a small piece of paper towel to cool the bit, some people blow compressed air in the hole. Like I said, there is several days worth of reading on this topic.

I believe the general consensus is that epoxy can take a little more heat and is possibly marginally more shock tolerant. Did I mention impact shock is a factor??

 

[Curly]

One other possibility to be aware of. If you clamp epoxy joints too tightly the glue squeezes out and you end up with a glue starved joint.

 

[bjbear76]

Sounds all too familiar to me too. I've let my blanks set overnight, they felt really good and solid, but when I go to drill, it separates at the joints (usually aluminum). It makes sense that the metal is heating up and causing the CA or epoxy to fail.
Thanks for the good suggestions.

 

[Fine Engineer]

Another issue I've read here recently is a possible bonding difference between the different kinds of epoxy. People have said they get better results with normal curing epoxy rather than the 5 minute variety. I don't know the physics or chemistry behind this, or if it is true, but it is another data point to consider.

I just did a copper pen myself, using thin CA glue, and had no problems drilling or turning (at least up to the point where I gouged out a couple of chunks of copper). Same material, different problem.

Jeff